Wowprogramming's documentation tends to be more consistent, but the problem is that it's only updated by a very small group of people (I don't actually know, but I'd guess 1-5 people) while anyone can add info to Wowpedia, so while the documentation can be inconsistent (eg. random functions not documented, writing quality varies wildly, some stuff is really outdated, etc.) it's also more thorough, with lots of notes and examples on usage, bugs, etc.
When in doubt, check
the default UI code to verify current API usage. Blizzard is generally pretty bad at writing efficient code, but one thing they
are good at is using descriptive variable names.